All earthquakes
1.9
very light
EARTHQUAKE DETAILS

M1.9 earthquake · 12 km North-West of Isole Tremiti (FG)

3 years ago · 12 Oct 2023, 19:38

A very light earthquake, probably not felt by people. At this depth the shaking is felt, but rarely causes damage.

Stronger than 85% of Italian events in the past year

Where

12 km North-West of Isole TremitiEarthquakes in the province of FoggiaEarthquakes in Puglia

How far away could it be felt?

A quake this small is usually not felt by people: only seismographs record it.

Statistical estimate from the Italian intensity attenuation model (INGV): actual perception depends on geology, buildings and depth. Very shallow events can be felt locally even below the threshold.

Earthquake map

4 events
Magnitude:lightweakmoderatestrong

The energy released

How much energy this quake unleashed, translated into everyday comparisons.

11kgof TNT equivalent
Less than the energy of a lightning bolt
M3
A magnitude 3 earthquake releases ×45 its energy
M1this quakeM3

Each extra magnitude unit releases about 32 times more energy: an M5 is not "a bit stronger" than an M4 — it is a different league.

Energy estimated with the standard Gutenberg–Richter relation; an average lightning bolt ≈ 1 billion joules. Indicative values.

The race of the seismic waves

Two waves set off from the hypocentre: the faster P wave arrives first with a sharp jolt; the S wave carries the actual shaking.

P waves — the first sharp jolt (~6 km/s)S waves — the strongest shaking (~3.5 km/s)
t ≈ 31 s

Animation sped up ~6× compared to reality.

  • San Severo
    71 km from the epicentre
    first tremor in ~12 s
    main shaking in ~21 s
  • Manfredonia
    78 km from the epicentre
    first tremor in ~13 s
    main shaking in ~23 s
  • Foggia
    88 km from the epicentre
    first tremor in ~15 s
    main shaking in ~26 s
  • Pescara
    106 km from the epicentre
    first tremor in ~18 s
    main shaking in ~31 s

Theoretical times with average crustal speeds: real values vary with geology. The gap between P and S waves is what earthquake early-warning systems rely on.

How deep it was born

18 km
medium depth
2 times the height of Mount Everest

At this depth the shaking is felt, but rarely causes damage.

in line with the area average (~13 km)

For the same magnitude, a shallow earthquake is felt much more than a deep one: the energy starts closer to the surface.

What kind of quake is this?

Aftershock

It is an aftershock: it follows a stronger quake (M2.2, 3 years ago) in the same area. Aftershocks are normal after an earthquake and tend to fade over time.

2.2
The mainshock
14 km South of Isole Tremiti
3 years ago · 18 Sept 2023, 14:33
Activity in the area right now (30 km radius)
0
last 24 hours
0
last 7 days
0
last 30 days
3 before0 after
this quake
Strongest of the sequence2.2

How often does it happen here?

about every ~11 days

Within 50 km of this epicentre, a magnitude ≥ 2 earthquake has occurred on average this often: 409 events in the last 12 years of the INGV catalogue.

An average computed on the recent past: it tells how used this area is to shaking, not when the next quake will come — earthquakes cannot be predicted.

The great earthquakes in this area's history

Almost a thousand years of catalogues: the strongest documented events within ~50 km.

18215.6
Costa molisana earthquake
22 November 1821 · 36 km from here
VII-VIIIRuinous: partial collapses in ordinary buildings, widespread heavy damage.
18895.5
Gargano earthquake
8 December 1889 · 48 km from here
VIIVery strong: hard to stand; chimneys and roof tiles fall, serious damage to weaker buildings.
18944.9
Gargano earthquake
25 March 1894 · 43 km from here
VIIVery strong: hard to stand; chimneys and roof tiles fall, serious damage to weaker buildings.
18924.9
Isole Tremiti earthquake
6 June 1892 · 13 km from here
VIIVery strong: hard to stand; chimneys and roof tiles fall, serious damage to weaker buildings.

Source: Parametric Catalogue of Italian Earthquakes CPTI15 (INGV, CC BY 4.0).

The closest seismic structure

Tocco Casauria-Tremiti

The epicentre lies about 12 km from Tocco Casauria-Tremiti, one of the seismic structures mapped by INGV geologists.

estimated maximum magnitude 7.5between 11 and 20 km deep

Faults are mapped to build better and understand the territory: knowing them says nothing about when an earthquake will occur, which remains unpredictable. Source: DISS 3.3 (INGV, CC BY 4.0).

Other quakes in the area

2.0
16 km North of Isole Tremiti
10 km North-East · 8 km
3 years ago
11 Oct 2023, 16:38
1.4
4 km South-East of Isole Tremiti
15 km South-East · 24 km
3 years ago
29 Sept 2023, 03:32
2.2
14 km South of Isole Tremiti
25 km South · 11 km
3 years ago
18 Sept 2023, 14:33

Data: INGV — National Institute of Geophysics and Volcanology (CC-BY 4.0)

Estimates computed by Meteare on INGV data (Gutenberg–Richter relation; Italian macroseismic intensity attenuation model).